20 questions...-3 to +7 LTFT adj on '07 5.3? Whats the deal?

[Chuck_yager]

Hey guys, this is my first time to post on here. Just want to start out by saying this is a cool group and a great product (EVEN IF THERE IS ON TCM SUPPORT...LOL ) I have been playing with the different tunes on my 7194 and I ran the 87 Octane tune and was pleased with the results, so I decided to see what the 91 octane tune has to offer. A big factor for purchasing this tool was to improve my fuel mileage after I installed a new set of 10 ply rated tires which brough my mpg down to around a best of 15 mpg. With the 87 tune I got back up to nearly 17.5 mpg, since installing the 91 tune I haven't noticed any improvement in fuel mileage. In fact, I started getting worse mileage since dialing in my LTFTs. I don't understand. The 87 thune needed a -3 adjustment to the fuel slope, so I did the same for the 91 and thought I'd be in the ballpark. After driving plenty of distance and viewing the numbers on the predator I was running close to -11.5. Ofcourse I changed the slope to +7 to get me closer and I am looking alot closer when I view the log. I try to follow the directions on the other posts for logging to make sure I am doing this right. My question is that normal to have such a swing in LTFT between the two tunes, and why is my fuel mileage so much worse on the same stretch of road with the 91? I have reset the slope to 0 and am going to try to drive it around to let it settle in to that setting and see what adjustments are called for then. I need to get the cable so I can run the programs to get me that warm fuzzy feeling though. I have LT headers and no cats, could that be causing an issue? I have the COT off and the time out(?) set to 60 seconds. Lew, I am becoming a big believer in what you can do and I would like to get you to work your magic on this beast once I get this straightened out so I can have the codes disabled for the CEL too along with really waking it up.

[06MonteSS]

np man...

resintall the tune and leave it as is... make sure you reset all parameters so that none of your previous adjustments are in it... you do that by going into Modify Tune - then select Reset All Parameters... answer YES to reset everything back to the default diablo tune settings, then install the tune....

then put on about 30-50 miles... then do a normal steady cruising log on the highway, keeping your rpms between 1800-2000...

[Chuck_yager]

Good deal! That's what I did when I got back from lunch. I'll get back to you when I have put the miles on. I am thinking right on the COT protection being off and the time out adjustment, right? Hopefully, I'll get that cable in the next couple of days and I can send you what I have so I can become DiabLew tuned! I can't wait! Thanks for the quick reply!

[06MonteSS]

yes, with no cat's on there, you can set the COT off and max out the time...

[derekg1469]

yea lew im kinda having the same problem my ltfts keep changing and so the program will tell me to lower the inj slopes. i do drive for about a week 300 miles the run again and it will tell me to increase by like 4 i do then run test for another week and vise-verse so i have just reset all parameters. and funny thing was after about 2 monthes of this i got it dialed in at 0 it was still off on my rpms but this has been the most consistent # from the program. i am not really beating any trucks like mine but factory im kinda dissapointed let me know what ya think if i should just go ahead and have you program it or wait for the cold air tube sorry to hijack your post just reminded me of what i am going through lemme know lew i dont want to have to pay ya twice just because of a air intank

[derekg1469]

ahhh.... theres my problem i just read the post about the 3rd gear yea i too have done that i will do a pull tommorow with dod off and in D this time and e-mail you with #s tommorw thanks again lew your awesome and to the posts good questions

[06MonteSS]

np man...

and no, you wouldn't have to pay twice... read my tuning info page heh... I don't charge ya again to make re-adjustments...

for your ltft's and slope adjustment... pick a nice warm/hot day... do a steady driving log, correctly (haha), and make your slope adjustment based on that...

and that's it.. done...

ltft's will always fluctuate and change - they're supposed to... that's how the ecm keeps the part-throttle AFR at the stoich 14.7 value....

you can log every week and get different results, due to air temp differences, weather conditions, etc etc, and you'll just be chasing your tail man...

[Chuck_yager]

Yeah, I noticed that. I reset my parameters and have settled on a -2 adjustment. I may go to -1 just b/c it was rainy and about 51* today when I looked at the log, but I am going to leave this for a while and see how it looks. I am plannig to find me the adapter this week so I can proceed to get your magic done. I am still a little puzzled about the fuel mileage part. It seems like they were better wen I had values at less than the 0 to -2 range when I had no adjustments. The wife's borrowing the truck and putting some good highway time on it tomorrow so I'll know how the last adjustment works out. On a side note, why aren't there any diablo products for the european stuff? We have an '04 VW Touareg V8 that I'd love to get a DiabLew tune on! Let me know if there's something you can do for that, I'd sure be interested.

[06MonteSS]

nah... nothing for those... different programming/modules...


**PUNCH!!** RED ONE!!!

[Chuck_yager]

LMAO!!!! Yeah, I love those new commercials!

[Chuck_yager]

**PUNCH** GREEN ONE!!! Can you help me with an idea I have been kicking around? I have the cable on its way (finally). I am debating the advantages/disadvantages of going with having work done on the 87 octane tune or the Diablo tune. I understand the 91 octance tune will gain more performance, but I am also trying to keep fuel economy in mind. Generally speaking is fuel economy going to be any better with the 87 tune or the 91 tune? Or, does it not matter which tune I am taking about b/c when you are finished with it I will be needing to run 91 octane? I really am struggling in my mind with the approximately $.30/gal difference from regular to premium fuel. I have a feeling that the best answer to this question is going to be suck it up sissy and pony up the dough since you are only talking about $5 per fill up or so. The other thing is can you program out/ turn off the Traction control and stabilitrack and have the lighn not come on? I hate those driver interference programs. I have noticed my traction control light flashing at higher RPMs when I am at WOT is the other reason for wanting it gone. Sorry for any repeats on this if there are any.

[06MonteSS]

fuel economy will be better than stock, using either tune, when I'm done with it...

but the diablo tune (91 octane tune) will have more performance, better power, etc etc...

but, the 87 tune will too, compared to stock, once i'm done with it...

I can disable the traction control... but not stabilitrak, that's not in the tuning file, that system is in a different module like the BCM (body control module) or the ABS module...

[Chuck_yager]

Latest update on LTFTs. I reset the tool to 0 adjustment on fueling and drove it a while longer, per Lew's recommendation, and decided to check my header and collector bolts like a good gear head should do, and that's when I saw it. Somehow the intake hose had pulled from the airbox lid and was just hanging there. After scratching my head for a second or two because I knew it was in place when I installed the headers, I put it back in its place and tightened the clamp for all I was worth. It seems as if that has had some effect on my LTFTs as they are alittle more in line with what I had with the 87 octane tune. I never imagined that something like that would seemingly cause such a thing. All that is making me wonder about the benefits of a CAI now....maybe later. Rather use the money for the tune right now. LOL

[06MonteSS]

a-HA!! good find....

yeah man, an air leak like that would definitely affect the fuel trims and throw everything off...

[Chuck_yager]

Lew, just triple verifying you got all you needed from me. I emailed you the cruise log, original tune, and last tune written (called custom tune) and the paypal has been sent as per directions. I sent the files through my cherokee.org mail account b/c I can see that one at work, but the paypal accout is my hotmail account (sorry if this causes any confusion). I finally feel like I got the LTFTs set where they need to be, and the DSlogRedux confirmed, so I quit jacking with it and decided to send it to you. I am sure you can see I haven't done anything for WOT yet. I figure you and I will go through that once you are happy with the cruising adjustments you are going to make. Looking forward to the "new" truck! LOL